The present disclosure relates to a decoding device, a decoding method, and a program, and particularly to a decoding device, a decoding method, and a program which are designed to easily generate substitute signals having little incompatibility when an error occurs during decoding.
From the past, there has been an encoding device which overlaps audio signals of adjacent blocks, and performs orthogonal transformation and encoding for the signals. A decoding device, which decodes encoded data generated in such an encoding device, performs inverse orthogonal transformation, and outputs audio signals, generates substitute signals for the purpose of masking an error when the error occurs during the decoding.
As a method of generating the substitute signals, for example, there is a method in which a pitch cycle is obtained and substitute signals are generated from past decoding signals based on the pitch cycle (refer to, for example, Japanese Unexamined Patent Application Publication (Translation of PCT Application) Nos. 2002-542518 and 2002-542519).
In the method of generating substitute signals disclosed in Japanese Unexamined Patent Application Publication (Translation of PCT Application) Nos. 2002-542518 and 2002-542519, an automated correlation between a decoding signal immediately before an error occurs and a past decoding signal traced back from the foregoing decoding signal by a predetermined number of samples is obtained for each of the predetermined number of samples, and a predetermined number of samples when the automated correlation becomes the maximum value is obtained as a pitch cycle.